The present invention relates to an LED power supply device. An exemplary power supply device is described in EP 1 374 366 B1 which is used to minimize the standby power requirements in a digital addressable lighting interface (DALI). DALI refers to an industrial standard used for implementing flexibility in the control of luminaries. In particular, the DALI standard specifies how to control and monitor the status of individual and group addressable lighting equipment such as electronic ballasts and illumination sensors.
An arrangement of an LED power supply device is shown in FIG. 4 according to the prior art. The arrangement includes a two-stage power supply device consisting of a primary stage 10, which is regulated and provided with a power factor correction and a secondary stage 14 which is coupled to the primary stage 10 via a transformer unit 12. The secondary stage 14 is connected at the output side via an output 16 to a power consumer (not shown) that receives power from the power supply device, such as an LED. An output-side smoothing capacitor 18 is provided to ensure that a direct signal that is output from secondary stage 14 is stripped of high-frequency components.
The primary stage 10 of the power supply arrangement of FIG. 4 is controlled by a control unit 20, which is in turn coupled via an interface module 24 to a DALI input connection (DALI line) 22. In addition, a voltage supply module 26 is coupled to the control unit 20, and receives supply voltage from the power supply input connection (Mains) 28. The voltage supply module 26 is connected in such a manner that the control unit 20 can be kept in continuous operation. This arrangement makes it possible to respond at any time to control request or status commands received via the DALI interface 24, particularly during periods when the power supply components 10, 12, 14 and the power consumer coupled to the output 16 are deactivated.
In a prior art power supply device of the type shown in FIG. 4, which embodies the basic principle set forth in EP 1 374 366 B1, a microcontroller is typically used to form the control unit 20 or DALI interface unit 24. Notably, to achieve continuous operation, the voltage supply unit 26 draws electrical power from the power supply input 28. This arrangement is disadvantageous in at least two respects. On the one hand, additional design or circuit outlay is used to support the continuous supply of voltage to the control unit 20. Additionally, the energy balance of a control device constructed in this manner may degrade due to the continuous electrical power consumption, particularly during off, idling or standby operating states of a power consumer connected at the output side 16. This is critical particularly for those arrangements in which the idling, standby or off phases are relatively long in comparison to activation phases, which may lead to the mean power drawn from the mains exceeding predetermined limits.